Known medical procedures involving, for example, intravascular delivery of a balloon or a stent using a catheter are performed with reference to a diagnostic image. For example, stenosis, blockage, and the like of a blood vessel are checked by observing fluoroscopic images, such as X-ray images which are continuously captured through an angiography method during a surgical operation using the catheter. Recently, a technique of collectively checking vascular cross-sectional images obtained through an intravascular ultrasonic (IVUS) endoscope, an optical coherence tomography (OCT) apparatus, an optical frequency domain imaging (OFDI) apparatus, or the like has come into widespread use.
In such procedures, the fluoroscopic images and the cross-sectional images are used mainly to perform pre-operative diagnosis or to check the effect of post-operative medical treatment. For example, when expanding a stenosed site of a blood vessel by inserting the stent into the blood vessel, a physician will check the overall shape of the target coronary artery through the X-ray image, thereby specifying the stenosed site of the blood vessel. The physician will also use the cross-sectional image of the stenosed site to grasp the condition of a disease inside the blood vessel, thereby determining the indwelling position, the size, and the like of the stent.
As a method of displaying obtained images, for example, JP-A-2007-282974 discloses that a position of an IVUS probe inserted into a subject is displayed on an X-ray image. In addition, JP-A-H05-64638 discloses a method in which a shifted position of an ultrasonic probe is detected through an X-ray fluoroscopic image. JP-A-H05-64638 also discloses that an ultrasonic image at a predetermined position is recorded and the recorded ultrasonic image is displayed in accordance with designation of a position performed by a user.